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Carbon print
A carbon print is a photographic print produced by soaking a carbon tissue in a dilute sensitizing solution of potassium dichromate. The solution also consists of carbon, gelatin, and a coloring agent. The process was created as a result of print fading in early photographic processes, and was patented in 1864 by Joseph Wilson Swan. An Overview and History of Carbon (Pigment) Printing The carbon process, initially a black and white process using lamp black (carbon black), was invented by Alphonse Poitevin in 1855. The process was later adapted to color, through the use of pigments, by Louis Arthur Ducos du Hauron in 1868. Carbon printing remained commercially popular through the first half of the 20th century. It was replaced over time by the dye-transfer process, chromogenic, dye-bleach (or dye destruction, i.e., Cibachrome) and, now, digital printing processes. The efficiencies gained through these more modern automated processes relegated carbon printing to the commercial backwaters in the latter half of the 20th century. It is now only found in the darkrooms of the rare enthusiast and a few exotic labs. Carbon printing relies upon the ability of gelatin, when sensitized to light by a dichromate, to become insoluble in water after exposure to sunlight, or its modern equivalent (UV). Three successive layers of gelatin, containing first yellow, then magenta and finally cyan pigment, are, one at a time, exposed, aligned (registered) and then transferred onto a white opaque support (substrate, base or carrier, i.e., paper or melinex) and processed in warm water (≈100 °F to 105 °F). A fourth layer of black was added later on to improve density and mask any spurious color cast in the shadows. The unexposed areas, which remain soluble in warm water, are washed away, revealing, according to the inverse of the exposure, the underlying white support. This creates a bas-relief effect of varying texture and finish on the surface of the print that is the unique signature of the carbon process. Each color carbon print requires three, or four, round trips in the darkroom to create a finished color print (see CMYK). An individual, using existing pigmented sheets and separations, can prepare, print and process enough material, 60 sheets including the support, to produce about 12 - 20" x 24" four color prints in a 40 hour week. *It should be noted here that the carbon process is typically used to produce; *:-Mono-chrome prints, usually B&W, but often sepia, cyan or any other preferred color. *:-Duo-chrome (duo-tone) prints, an effect many printers are familiar with, using complementary or associated colors to their best effect. *:-Tri-chrome prints, a traditional full color print made by layering Y, M & C pigment sheets. *:-Quadra-chrome prints, basically the same full color print as the tri-chrome with the added finishing layer of black (K) to add density and mask spurious color in the shadows. *That noted, any combination of layers, in any color, are possible to achieve whatever ends the printer desires. *Its also important to mention here that there are two primary techniques used in carbon printing, single transfer and double transfer. This has to do with the negatives (separations) being right or wrong reading and the image "flopping" during the transfer process. * Because the carbon printing process uses pigments instead of dyes, it is capable of producing a far more archivally stable (permanent) print than any of the other color processes. Good examples of the color stability of pigments can be found in the paintings of the great masters, the true colors of which, in many cases, have survived all these centuries. A more contemporary example of the color stability of pigments is found in the paints used on automobiles today, which must survive intense daily exposure to very harsh lighting, under extreme conditions. The useful life of many (but not all) pigment formulations has been projected out to be several centuries and beyond (perhaps millennia, if cave paintings of Lascaux, the wall paintings in the tombs of the Valley of the Kings and the frescoes of Pompeii are relevant examples), often being limited only to the useful life of the particular support used. Additionally, the use of pigment also produces a wider color gamut than any of the other color processes, allowing for a greater range and subtlety of color reproduction. Though carbon printing always has been, and remains, a labor intensive, time consuming and technologically demanding process, there are still those that prefer the high aesthetic of its remarkable beauty and longevity over all other processes. Chronological History of Carbon (Pigment) Printing See also * Woodburytype, a variation of the carbon process External links * Alternative Photography - Covering the Carbon Printing Process * Art & Soul Photo, Seattle, WA - Contemporary Color Carbon Printing Services * Bostick & Sullivan, Inc. - Carbon Printing Methods & Materials * Fresson, Paris, France - Carbon Printing Services for over a Century * Photographers Formulary - A Resource for many Historic & Alternative Photography Supplies cs:Uhlotisk es:Impresión al carbono sr:Карбонски отисак Categoría:Procesos fotográficos Categoría:Impresión Categoría:Fotografía Categoría:Diccionario de cerámica inglés - español: C Categoría:Photographic processes Categoría:Non-impact printing Categoría:Diccionario C